Third interstellar celestial body? – A11pl3Z causes excitement

So far, two interstellar celestial bodies have been discovered hurtling through the solar system. Evidence of the next one is now mounting.

(Image: Vyas Abhishek/Shutterstock.com)

Jul 2, 2025 at 1:43 pm CEST

3 min. read

By

Martin Holland

On Tuesday, telescopes in Chile may have discovered the third interstellar object in the solar system, known as A11pl3Z. This is according to reports from the European Space Agency and various astronomers on Bluesky. The responsible offices at the US space agency NASA and the Minor Planet Center of the International Astronomical Union have already confirmed the discovery. However, it remains to be seen whether it is actually a celestial body that is just passing through and will leave the solar system again. However, the values determined so far and the trajectory calculated from them strongly suggest that it is.

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Astronomers may have just discovered the third interstellar object passing through the Solar System! ESA’s Planetary Defenders are observing the object, provisionally known as #A11pl3Z, right now using telescopes around the world.

— ESA Operations (@operations.esa.int) Jul 2, 2025 at 10:23

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To be expected with newly discovered objects moving slowly, things are updating. New precovery observations from I41 now span back to June 14th, 2025. The eccentricity as dropped a bit to ~6, which is still almost double 2I Borisov (3.36). Updated orbit plot here: 🔭 (Image from Saguaro Observatory)

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— David Rankin (@asteroiddave.bsky.social) Jul 2, 2025 at 07:06

According to reports, the celestial body was discovered as part of the Deep Random Survey project, for which amateurs have access to a telescope in Chile. The object has now also been detected with other devices, and there are already reports that there is also evidence in older data from other observatories. According to the very first calculations, A11pl3Z has an eccentricity of well over 10, whereby any value over 1 means that the object is not in orbit but is merely passing our sun. Even if the value has since been corrected downwards to just over 6, this would still be almost twice as much as the previous record holder 2I/Borisov.

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Interstellar objects are celestial bodies that are not bound to a star and only pass through star systems like ours. Such a passage has only been observed for two objects so far, 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019 and 2020. Both were of great interest to researchers because they came unusually close to us as objects from outside. A11pl3Z could now be the hoped-for third research object. According to current calculations, it will approach the orbit of Mars in the fall. At its closest approach, it will therefore be about twice as far away from the sun as our Earth.